In 1906, physician August von Wassermann adapted Jules Bordet's complement-fixation reaction to develop what is now called the Wassermann test, a blood-serum reaction that detects antibodies to Treponema pallidum, causative agent for syphilis. It accurately indicated presence of the dreaded sexually transmitted disease, a potentially lethal condition which can have a very long latency period with no discernable symptoms. The test has been modified and improved in the century since, but the basic principles of the Wassermann reaction remain unchanged. Wassermann also researched cholera, tetanus, and cerebrospinal fever, and developed a test for tuberculosis and an antitoxin against diphtheria. He studied under Paul Ehrlich, who later developed the first effective therapy for syphilis, and he worked under bacteriologist Robert Koch, who determined the cause of tuberculosis.